Our transcription: The actual temperatures at which magma forms or as crystallizes are influenced greatly by its water content. In general, the greater the water content, the lower the temperatures. By showing that magma crystallizes in a piecemeal fashion, Bowen provided an explanation for why plutonic rocks contain so many types of crystals, and volcanoes, so few. But Bowen's work has other important implications. It suggests that different kinds of igneous rocks can form from a single parent magma.